bigbronco

I have a 1985 porsche 944 that i bought two weeks ago. I have had no problems with the car until yesterday. Driving to work, it was running perfect. After work, when i went to start it, it would turn over but not start. Upon getting it home, I checked for fuel and spark and had no spark. With a voltometer, I checked the positive side of the coil to the negative side of the battery and had 12 volts. I then checked the negative side of the coil and the positive side of the battery and had nothing. I assumed the coil was bad so I removed it. Between the two sides of the coil I had 1.0 volts resistance. On the high side I had 5.8 volts resistance. Out of curiousity, I checked the two coil wires while they were disconnected from the coil and had 12 volts between them.

Long story short...when the negative side touched the terminal of the coil, I lose my voltage on the voltometer. When it's not touching it, I have 12 volts...???

Does this mean a bad coil?

Thanks,
Michael

Perculator00

I have no idea on the answer to that, but I am too wondering how to tell if the ignition coil is bad. Iv had my turbo for over 3 years, and far as I know its never been touched. I am in the process of putting in new wires, cap, rotor, (spark plugs are new already) and I too have hard starts. It turns over but NO start. Like it keeps trying and trying. Im hoping its the ignition coil in my case thats causing that.

Black51

First off, are you getting tach bounce when cranking?

Ronin-951

Look for 1/16" bounce - thats a quick test of the Speed/Reference senders - Bounce=Good. DME wont operate without that. The coil resistance test is in 'Ohms', use the lowest scale possible, but it's best to test for function by manually firing the coil. The coil always has +12vdc [Black wire] on one side with the key switch ON, it is fired when the DME supplies a ground pulse.Pull a spark plug, connect the plug to the coil to distributor wire at the distributor side while leaving the coil side connected, and lay it on the block so that the threads are grounded, Turn the key ON, take a short length of wire from the battery Negitive and touch it to the coils Green wire, [Negitive from DME] Spark plug should fire once for every contact. Another common failing is the DME Relay. Check out 'Clarksgarage.com' for a comprehensive troubleshooting tree.